圆管中分层层流流动的新模型及减阻规律

本文提出了研究圆管分层层流流动的新模型，并利用该模型研究了圆管分层流动速度分布规律，得出了速度场解析表达式，最后，研究了分层流动的阻力规律，为分层掺气减阻提供了理论依据．算例表明。

牛顿流体紊流—幂律流体层流的圆管分层流动规律

从流体力学中N-S方程与雷诺方程出发,建立了圆管两相中一相为幂律流体而另一相为牛顿流体分层紊流-层流流动的数学模型。通过两相分层紊流-层流的相互作用的流体力学分析,提出了两相流动界面的耦合条件,从而得到了一组完整描述两相圆管分层紊流-层流的数学方程,通过数值求解分层流的数学方程,得到了对工程实际应用有重要价值的流动规律。应用圆管两相分层紊流-层流的流动规律,可以实现高粘流体的高效率输送。

A Model of Turbulent-Laminar Gas-Liquid Stratified Flow

The time-dependent liquid film thickness and pressure drop are measured by using parallel-wire conduc tance probes and capacitance differential-pressure transducer. A mathematical model with iterative procedure to calculate holdup and pressure drop in horizontal and inclined gas-liquid stratified flow is developed. The predictions agree well with over a hundred experimental data in 0.024 and 0.04 m diameter pipelines.

The Impact of the South Asia High Bimodality on the Chemical Composition of the Upper Troposphere and Lower Stratosphere

The South Asia High （SAH） is the dominant feature of the circulation in the upper troposphere and lower stratosphere （UTLS） during the boreal summer, and the upper tropospheric anticyclonic circulation extends into the lower stratosphere. The preferred locations of the center of the SAH occur in two different regions, and the center can be located over the Iranian Plateau or over the Tibetan Plateau. This bimodality has an impact on the distribution of chemical constituents in the UTLS region. We analyzed water vapor （H20）, carbon monoxide （CO）, and ozone （03） data derived from the Aura Microwave Limb Sounder （MLS） and total column ozone data from the Ozone Monitoring Instrument （OMI）. For the Iranian Plateau mode of the SAH, the tropospheric tracers exhibited a positive anomaly over the Iranian Plateau and a negative anomaly over the Tibetan Plateau, whereas the stratospheric tracer exhibited a negative and a positive anomaly over the Iranian Plateau and the Tibetan Plateau, respectively. For the Tibetan Plateau mode, however, the distribution of the anomaly was the reverse of that found for the chemical species in the UTLS region. Furthermore, the locations of the extrema within the anomaly seemed to differ across chemical species. The anomaly extrema for H20 occurred in the vicinity of the SAH ridgeline, whereas CO and O3 exhibited a northward shift of 4-8 degrees. These impacts of the variation in the SAH on the chemical constitutes in the UTLS region can be attributed in part to the dynamical structure delineated by the tropopause field and the temperature field at 100 hPa.

Study of the Jet-Induced Mixing of Two-Layer Density-Stratified Fluid in a Rectangular Tank

The mixing phenomena of a two-layer density-stratified fluid induced by a jet in a tank are experimentally investigated. The upper and lower fluids are water and a NaCl-water solution, respectively, with the lower fluid issued vertically upward from a nozzle at the bottom of the tank. The jet Reynolds number Re, defined by the jet velocity and the water kinematic viscosity, ranges from 90 to 4,200. The mass concentration of the NaCl-water solution Co is less than 0.08. The flow visualization makes clear the jet behavior relative to the density interface between the upper and lower fluids. The measurement of the concentration distribution of the water paint issued with the jet highlights the effects of Re and Co on the mixing between the jet and the ambient fluid. The measurement of the fluid velocity distribution with a PIV （particle image velocimetry） system successfully elucidates the relationship between the velocity field and the resultant mixing.

Study on Electrical Potential by Buried Source Electrode within the Horizontally Layered Half-space Model

The paper first studies the analytical expression of electrical potential by a point current source in a uniform half-space medium,and then focuses on the distribution of electrical potential in a horizontally layered half-space model by a point current source within the surface layer or the bottom layer.Finally,the electrical potential by a source electrode in any layer of a layered half-space model is presented.

Numerical Study of the Mixing of Density-Stratified Fluid with a Jet

Density stratification of LNG （liquefied natural gas） is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is considered to a promising technique to prevent and eliminate stratification in LNG storage tanks. This study is concerned with the numerical simulation of a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The jet behavior was investigated with the laboratory-based experiment of the authors＇ previous study. A numerical method proposed by the authors is employed for the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number （Re） defined by the jet velocity and the nozzle diameter ranges from 95 to 2,378, and the mass concentration of the NaCl-water solution Co is set at 0.02 and 0.04. The simulation highlights the jet-induced mixing between the upper and lower fluids. It also clarifies the effects of Re and C0 on the height and horizontal spread of the jet.

Experimental Investigation of Flow Instabilities in a Laminar Separation Bubble

The present paper reports the results of a detailed experimental study aimed at investigating the dynamics of a laminar separation bubble, from the origin of separation up to the breakdown to turbulence of the large scale co- herent structures generated as a consequence of the Kelvin-Helmholtz instability process. Measurements have been performed along a fiat plate installed within a double contoured test section, designed to produce an adverse pressure gradient typical of Ultra-High-Lift turbine blade profiles, which induces the formation of a laminar separation bubble at low Reynolds number condition. Measurements have been carried out by means of comple- mentary techniques： hot-wire （HW） anemometry, Laser Doppler Velocirnetry （LDV） and Particle Image Veloci- metry （PIV）. The high accuracy 2-dimensional LDV results allow investigating reverse flow magnitude and both Reynolds normal and shear stress distributions along the separated flow region, while the high frequency response of the HW anemometer allows analyzing the amplification process of flow oscillations induced by instability mechanisms. PIV results complement the flow field analysis providing information on the generation and evolu- tion of the large scale coherent structures shed as a consequence of the separated shear layer roll-up, through in- stantaneous velocity vector maps. The simultaneous analysis of the data obtained by means of the different meas- uring techniques allows an in depth view of the instability mechanisms involved in the transition/reattachrnent processes of the separated shear layer.

Supersonic Flow Structure in the Entrance Part of a Mixing Chamber of 2D Model Ejector

The paper deals with experimental and numerical results of investigation into supersonic and transonic flow past a two-dimensional model ejector. Results of optical measurements show a flow structure and flow parameter development in the entrance part of the mixing chamber of the ejector. Numerical results are obtained by means of both the straight solution of shock waves in supersonic flow field using classical relations of parameters of shock waves and the Fluent 6 program. Results of numerical solutions are compared with experimental pictures of flow fields. Flow structure development in the mixing chamber is analysed in detail.

Sedimentary filling and sequence structure dominated by T-R cycles of the Nenjiang Formation in the Songliao Basin

The Nenjiang Formation in the Songliao Basin is a symmetrical sequence of progradation-retrogradation,and is formed in the transgression cycle and regression cycle(T-R cycles)of the base level of deposition.We analyzed the drilling,well logging,core data,and seismic profiles of basin level,and by using the sequence stratigraphy,identified one secondary sequence boundary,two third-order sequence boundaries,and eight fourth-order sequence boundaries in the Nenjiang Formation.These eleven sequence boundaries can be divided into structural unconformity,depositional unconformity,flooding surface,and forced regression surface.Therefore the Nenjiang Formation can be subdivided into one secondary sequence,three third-order sequences,and ten fourth-order sequences.We have restored the sedimentary filling evolution within the stratigraphic framework of fourth-order sequences in the Nenjiang Formation.The sedimentary period of the first member of the Nenjiang Formation was corresponded to the global transgression period,which is also the development period of transgression cycle(T cycle),when the lake basin had the largest scope and deepest sedimentary water,the SB07(the maximum flooding surface)was formed on the top of strata during this period;covering above the SB07,there developed a set of condensation layer-oil shale,which is distributed in the whole basin and is the important source bed and regional cover.Therefore,a retrogradation sequence was formed in the T cycle of the first member of the Nenjiang Formation,characterized by the retrograding delta at a low angle.The delta has a giant front,a small plain,and many underwater distributary channels.Meanwhile,large gravity flow channels and sublacustrine fans are developed in the front of the delta.During the depositional period of the second member of the Nenjiang Formation,the R cycle began to develop due to the compression of the pacific tectonic domain;the source direction rotated 90°along with the eastern uplifting of the basin,and formed a series of east-west prograded and forced retrogradations.The prograding delta at high angel was developed in the interior of the sequence;the delta had a small front,a giant plain,and fewer underwater distributary channels,with the collapse at the foreslope,forming a series of slump fans.The slump fans can be divided into three types:discrete type,superimposed type,and fluid type.We built a whole"triad model"of the slump fan.Pointed out that the sequence of forced retrogradation formed by R cycle is a good structural mark of basin optimization,and rejected the viewpoint of"transgression"in the Nenjiang Formation of the Songliao Basin.

Subjective Social Status,Income Inequality and Subjective Perceptions of Mobility(2003-2013)

Using a sample of over 90,000 urban and rura1 residents from the Chinese Social Survey(CSS)and China Genera1 Social Survey(CGSS)from 2003 to 2013,we analyzed the structural features and influencing factors underlying subjective social status in China.Our findings indicate that over these years,such identification has consistently assumed the shape of a bowling pin:those who“identify with a low social status”account for more than half of respondents,a much higher proportion than in most countries.At the individual level,the net effect on subjective social status of such objective indicators as education,income and occupation has been relatively small,and lessened over the ten years.The correlation between subjective perceptions of mobility and subjective social status is quite strong,but the upward impetus provided by perceptions of upward mobility weakened over the period.At the macro-level,the tempo of economic growth failed to raise the level of class identification,and income inequality had a markedly negative effect.Our research findings further demonstrate that curbing the income gap and increasing opportunities for mobility are important for raising the level of class identification during the transition period.